Farinaceous products comprising dehydrated fruits, grains and vegetables, in particular potatoes, have become extremely popular. Among the most popular products are fabricated potato chips, tortilla chips, pretzels and extruded or puffed products. Farinaceous products are generally made by adding ingredients such as, water, flavoring, emulsifiers and other starch materials to a dehydrated product. The mixture is then typically extruded and/or sheeted and cooked (e.g., baking, frying) to form the final product. Control over the taste and other organoleptic properties of the finished product is largely dependent on the physicochemical and organoleptical properties of the starting dehydrated product.
Among the most popular dehydrated products included in the preparation of farinaceous products are dehydrated potato flakes, flanules, and granules. Two basic processes are employed to produce dehydrated granules, flanules and dehydrated potato flakes. The initial preparation for both processes is typically the same. Raw potatoes are washed, peeled, and inspected to remove any defective potatoes. The good potatoes are cut into slabs, rinsed with room temperature water, and fed into the cooking operation, which is divided into two cooking steps. The first cooking step is a pre-cook step which partially cooks the potato at about 155° F. to about 175° F. (the activation temperature at which hydrolysis of protopectin can occur) and solubilizes some of the starch. During this step, swelling and gelatinization of the starch starts to occur. Following the pre-cook, the potatoes are cooled in water which causes the solubilized starch to precipitate out of solution, also known as retrogradation. In the case of flanules, and in the case of some types of flakes (i.e. some flakes used to produce fabricated snacks), the precooking and cooling steps are omitted. The second cooking step involves cooking the potatoes in a steam cooker that gelatinizes the starch and prepares the potatoes for dehydration. After this point in the process, the granule and flanule process differ from the flakes process. The granules and flanules process differs from the flake process in that the drying step is gentler and does not destroy potato tissue as does the drum drying that is more commonly used in the flaking process. Drum drying relies primarily on conduction heat transfer, which can be inefficient and detrimental to product quality. In the case of flanules, the drying operation includes fluidization and air lift drying, which are both based on convection heating.
Secondly, the dehydration step is much slower, causing retention of potato granules in the system for long periods. Thirdly, the granulation procedure differs from the flaking process in the drying procedure employed, whereby a portion of the granules, which are first dried, are recycled back into the stream of cooked mashed potatoes. This procedure is known as the add-back process.
Conventional methods for processing potatoes into dehydrated products have certain disadvantages. In the conventional processes for making potato flakes and granules, the potatoes are subjected to pre-cooking, cooling, cooking, and a number of other steps that reduce and change the original potato flavor and starch functional properties. Typically, the potatoes are washed, peeled, blanched, precooked and cooled before the cooking step. The potato slices are generally transported by water. This requires a substantial use of water and energy. The steps of water pre-cooking and cooling result in substantial loss of water soluble flavor precursors (or flavor components) and various aqueous phase reactions that degrade the taste and quality of the dehydrated product. Additionally, a considerable loss of the positive volatile flavor components can occur during drying. From an economic standpoint, these processes require a considerable expenditure of energy, time, and money in the pre-cooking, cooling, cooking, and drying steps. In addition to loss of flavor, from up to about 10% of the potato product can be lost during peeling. During the step of peeling of potatoes, high steam pressure is used to soften the skin from the potato tissue. This forms the so called “peel ring”, which is a thin layer of cooked starch surrounding the potato. Later during cooking this thin layer represents swollen starch which delays the heat transfer rate to the center of the potato pieces, causing uneven cooking of potatoes, resulting in a combination of raw potato pieces and overcooked potato pieces.
Another disadvantage of conventional processes for dehydrating potatoes arises because of the relatively long cooking time (up to about 45 minutes) needed to thoroughly cook the raw potato. The consequence of slow cooking is also the substantial use of energy needed to cook the raw product. Such prolonged cooking time of the potato destroys vitamins, reduces initial concentration of desirable flavor precursors, contributes to the formation of processed flavors, and increases cell damage.
A further disadvantage of conventional processes is that they can not be used efficiently to produce consistent quantities of high quality potato flakes, flanules, and granules suitable for use in farinaceous products. Additionally, in most cases the primary processes are not designed to produce flakes or granules having the characteristics suited, to say extrude or form a sheetable dough, but rather aimed at producing an ingredient for a completely different use such as rehydration for table use (e.g., mashed potatoes), or low shear forming potatoes for intermediate moisture products, such as, potato pancakes or French fries.
Accordingly, it is an object of the present invention to provide an efficient method for dehydrating fruits, vegetables, and grains, in particular potatoes, based on energy consumption and potato losses.
Another object of the present invention is to provide a process for making dehydrated potato products which enhances cooking to obtain key material transformations, while resulting in significantly shorter cooking residence times, and improved quality.
It is another object of the invention to provide a method for producing high quality, low cost dehydrated potato products using a method that is simple, quick and economical.
Still another object of the present invention is to provide a process for making dehydrated potato products, which eliminates the need for precooking and cooling of the raw potatoes.
It is another object of the present invention to provide dehydrated potato products particularly suitable for use as part of the dough used to make fabricated farinaceous products such as fabricated potato snack pieces.
It is further an object of the present invention to provide dehydrated potato products having improved nutritional value, color and processing quality over conventionally produced flakes, flanules, or granules.
It is further an object of the present invention to provide dehydrated products having an increased level of flavor precursors as compared to conventionally produced products.
It is another object of the present invention to provide dehydrated potato products particularly suitable for use in providing reconstituted mashed potatoes with improved flavor, texture, and shelf life.
These and other objects of the invention will become apparent from the following disclosure and claims.